This invention relates to the use of a linear analog sensor to measure thickness of non-metallic skin material, such as polymeric skin material. More specifically, the present invention relates to the use of a linear analog sensor to measure the thickness of polymeric skin material suitable for use on an automotive instrument panel, to thereby provide more accurate information regarding skin thickness for other manufacturing steps that require accurate skin thickness determinations, such as laser scoring or weakening of the skin at a desired location for placement of an air-bag deployment system.
In various commercial assembly applications, there remains a constant need to develop a reliable technique to more accurately provide information regarding thickness of a non-metallic component, such as a polymeric material, which includes plastic or elastomeric type skin material. Such information, of course, would be critically needed in those situations where the polymer material at issue requires another downstream manufacturing operation, which may rely upon skin thickness as a critical variable.
For example, in the automotive field, a variety of disclosures exist concerning the creation of a tear seam for the purpose of improving the performance of an air bag deployment system. Examples of such air bag cover tear seams are disclosed in U.S. Pat. Nos. 5,072,967; 5,082,310; 5,316,822 and 5,632,914. As disclosed therein, tear seams are prepared by forming such seam in the backside of a polymeric skin material. In addition, the seams are provided in various configurations, with the most common having a C, H, U or X-shape and wherein the pattern ultimately defines the number of air bag deployment doors required in the substrate.
That being the case, in the course of manufacturing skin material for use on an instrument panel, wherein the skin must be weakened at selected locations, it is critical to have some reliable indication of skin thickness, so that the weakening, scoring or tear seam formation, which occurs in a downstream process, can be properly regulated. That being the case, there remains a constant need to develop reliable techniques to evaluate thickness in non-metallic/polymeric type skin materials.
Of course, to date, a number of techniques have been advanced to measure thickness of a given non-metallic part. For example, it has been known to use lasers or other optical means to scan the surface of a fixture, followed by a subsequent scan after the plastic skin or shell is placed therein. Such method has been found to provide inconsistent thickness measurements due to varying reflectivity of the surface and a variety of other unknown factors.
Accordingly, it is an object of this invention to overcome the disadvantages of prior art designs and provide a new apparatus and method for detecting part thickness in non-metallic/polymeric type materials.
In broad aspect, the present invention relates to a linear analog inductive sensor apparatus that is employed to measure the thickness of a non-metallic/polymeric type material at any point along the surface thereof. In method form, the invention relates to placing the sensor in contact with the surface of the non-metallic surface, whose thickness is to be determined, wherein the non-metallic material is itself placed over a metallic target material. The sensor thereby detects and measures the distance between its contact point on the surface, to the target, which therefore provides an accurate and reliable measure of the non-metallic material thickness. The invention herein therefore can be applied to any non-conducting material, such as plastic or a composite/laminate material, rubber or fabric.
In further aspect the present invention relates to a process for measuring and recording the thickness of an automotive trim panel material to generate a cross-sectional thickness profile comprising the steps of contacting a first surface of the material at a plurality of positions with an inductive sensor, contacting a second and opposite surface of the material at a corresponding plurality of positions with a metallic object, converting the output of the sensor into a value that represents the thickness of the material at said plurality of positions, generating a cross-sectional profile of thickness in said material as between said plurality of positions, and communicating said cross-sectional profile of thickness in said material to a controller which is in communication with a cutting assembly to cut said material to a desired thickness, wherein said controller adjusts the thickness of a cut into said material based upon said cross-sectional profile thickness in said material to provide a cut of desired thickness.
In alternative embodiment the present invention relates to a process for measuring and recording the thickness of an automotive trim panel material to generate a cross-sectional thickness profile comprising the steps of contacting a first surface of the material at a first position with an inductive sensor, contacting a second and opposite surface of the material with a metallic object, converting the output of the sensor into a value that represents the thickness of the material at said first position, contacting said first surface of the material at a second position with said inductive sensor, contacting a second opposite surface of the material at said second position with a metallic object, converting the output of the sensor into a value that represents the thickness of the material at said second position, and generating a cross-sectional thickness profile in said material as between said first and second positions.
In yet further alternative embodiment, the generated cross-sectional thickness profile is communicated to a controller which is in communication with a cutting assembly to cut said material to a desired thickness, wherein said controller adjusts the thickness of a cut into said material based upon said cross-sectional profile thickness in said material to provide a cut of desired thickness.